I believe this is the safest angle combination to use. For non-symmetrical screening such as elliptical, a 60 degrees difference between dominant color (C, M, K) is required to achieve smooth rosette formation.

Min there should be 30deg diff between each colours to avoid moire but since there are 4colours we need to compromise some where so we choose yellow to be at zero as this is the least visible colour and then we put cyan at 15 deg. At 45 degrees the zagged formations at the edges are not visible so its best to use 45angle for single colour jobs.

Most jobs containing photos have more magenta than black so 45deg is prefered to magenta than for black in 4 colour jobs

Swapping screen angles is helpful sometimes

For highest quality reproduction it was common practice years before digital screening, not to adhere to a fixed angle per color, but to examine each picture and decide on the best screen angles according to the specific image content.
As a general rule, the two most dominant colors were placed 60 degrees apart, regardless of the color, especially for Duotones and Tritones.
Since objectionable patterning caused by Yellow moire was a real problem in some images, in images that had a lot of Yellow and very little information in the Black separation, angles of the Y and K were were swapped. In these cases a little Black Moire in the darker shadows was hardly noticeable, while the annoying pattern caused by the Yellow was avoided.
Another workaround was using a coarser screen ruling or a "non directional" screen for the Yellow separation for all images.
Flat tints of colors (vector based) "benefit" noticeably from such manipulations.

I met one problem recently. The artwork back side is gray scale. I guess the angle of K is 75, the customer returned all the order because back side some lines wavy, they should be straight. Then I exchanged the M and K angle(K 45), and everything is nice.
I do not know why, generally every angle should be fine. It is just one gray scale, no combination color.

I met one problem recently. The artwork back side is gray scale. I guess the angle of K is 75, the customer returned all the order because back side some lines wavy, they should be straight. Then I exchanged the M and K angle(K 45), and everything is nice.
I do not know why, generally every angle should be fine. It is just one gray scale, no combination color.

I use 175dpi to output the CTP the fist time, and 195dpi the next time.